Telephone trunk-release system.



J. L. E. MEYER.

TELEPHONE TRUNK RELEASE SYSTEM.

APPLICATION FILED JUNE 28, I909.

Patented Nov. 23, 1915.

2 SHEETSSHEET I J. L. E. MEYER.

TELEPHONE TRUNK RELEASE SYSTEM. APPLICATION FILED JUNEZB. 1909.

Patented Nov. 23, 1915.

2 SHEETS-SHEET Z.

. time STATES Enron. I

JOE-IAN L. E. MEYER, OF CHICAGO, ILLINOIS, ASSIGNOR. TO AUTOMATICELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOISTELEPHONE TRUNK-RELEASE SYSTEM.

met res.

To all whom it may concern:

. Be it known that I, J OHAN L. E. MEYER, a. citizen of the UnitedStates of America, and resident of Chicago, Cook county, Illinois, haveinvented a certain new and useful Improvement in Telephone Trunk-ReleaseSystems, of which the following is a specification. j

h ly invention relates to telephone eX- change systems of thatparticular character in which line switches are employed-that is to say,switches that are individual to a line, such as a subscribers line or atrunk line, and in which each line switch is provided with a releasemagnet which, when energized, serves to break or release the trunkingconnection established by the switch. in systems of this kind the saidmagnet has been energized by a trunk-release circuit including a thirdconductor of the trunk extending from the line switch to a selector orconnector or other similar switch. It was found, however, that the saidmagnet occasionally failed to respond in the desired manner,particularly if the trunk was quite long.

My invention contemplates, therefore, an improved arrangement wherebythe said release magnet is energized from a local grcund,which localground is closed by a relay controlled over the trunk-release circuit,whereby only a relatively small amount of current is necessary in thetrunk-release circuit in order to accomplish the energiz ing of therelease magnet, and whereby the release of any established trunkingconnection is made more certain.

My invention also contemplates an improved arrangement whereby therelease trunk between switches serves not only as a part of theenergizing circuit of the release magnet of the line switch, but also asa part of the supervisory circuit for giving a signal at one end of the,trunk as soon as the other end thereof is seized by the saidline switch.

To this and other useful ends my invention consists in mattershereinafter set forth and claimed.

Inthe accompanying drawings Figure 1 represents diagrammatically asubscribers substation A the line conductors of which are allotted tothe line switch C, a master switch D that controls the plungers of thegroup of line switches of which C is 1. 1ne1n Specification of LettersPatent.

Application filed June 28, 1903. Serial No. 564,681.

Patented Nov. 23, 1915.

her, and a first selector switch E, in a system embodying the principlesof my invention.

In Fig. 2 there is diagrammatically shown a connector switch F connectedwith the terminals of the ringer generator H, and the busy'signalingmachine I; and the line'conductors of the substation A are shownallotted t0 the line switch C, which is like the line switch C; and acentral oitice'battery is shown at B having its positive terminalpreferably grounded at G. Figs. 1' and 2 taken together representdiagrammatically a connection established between the subscribersstations A and A through the medium of central office switchingapparatus comprising my improved releasing arrangement.

The substation A maybe of any suitable or approved type. The one inconnection with which I have elected to describe my invention comprisesa receiver 2, switch hook 3 for controlling the substation circuits,which controlling operations are accomplished through the medium of anysuitable means, such as the cam arms 4, 5 and 6. As the switch hook islowered the cam arm 4 momentarily presses the release springs 7, 8 and!)into contact, whereby the line conductors may be groundedsimultaneously.When the switch hook is down the cam arm 5 is maintained in contact withthe spring 10, thereby bridging across the line conductors the ringer 11in series with the condenser 12. hen the switch hook is lowered thesprings 13 and 14 are also carried out of engagement. thus opening thelocal battery circuit which comprises the primary winding 15 in serieswith the transmitter 16'and battery 17. The substation ground circuit isnormally broken between the cooperating ground springs 18 and 19 by thecam arm 6; but when said springs are together ground potential isprovided to the ground post 20, and to the release'spring 7, as isusually the case in telephones of this type. Being an automaticsubstation it is provided with the 'usual vertical and rotary impulsesprings23 and 24. 'The substation is, of course, provided with a dial(not shown) which is secured to the shaft 25, together with the lockingdog 26. Furthermore, there is a locking cam 27'that locks the dog26'while the receiver is on the switch hook to prevent a rotation of thedial. For Operating theimpulse springs 28 and24 the CIT ' impulse occursWhen the substation is provided with an impulse wheel 28 that is securedto the shaft 25. This impulse WhEGl carries on its. periphery theso-called vertical impulse memos), and

the first digit the rotary impulse tooth 30 presses the impulse spring24 onto the ground post 20, thereby grounding the retary line conductor31, which provides a preliminary impulse for operating the line switchC; Theimp'ulse teeth 29 are so arranged that when the dial is drawn downthe impulse spring 23 is not carried into engagement with the groundpost 20; but as the dial returns, first the Vertical teeth 29 pressthevertieal'impulse spring 23' onto the ground post, thereby grounding thevertical line conductor 32; and after they havecoinplet'ed their WO'Ik'the rotary" impulse spring 24 is carried ontothe ground post 20 once. Aslong as the dial i'soat of normal position the dog 26 permits thesprings 33 and 3 1- to disengage, thus pre venting the impulses that aredelivered to either line conductor from passing to the other. I I j Themeans whereby the subscriber may signal another comprises the push"button spring 35 which normally engages the contact point 36; but whenthe button 37 is pressed the spring 35 is carried onto the contact point38; whereby the vertical line conductor 32 is grounded.

- The line switches C and C and the master switch D are of the typedisclosed in English Patent No. 26,301 of 1906, and in the Illinois, ofJune 6, 1908.

The first selector switch E is of the gen eral type shown in UnitedStates Letters Patent No. 815,321,granted March 13, 1906, to Keith,Erickson & Erickson. In this in- American Telephone Journal of Chicago,

stance, however, the bridge-cut-"ofi" relay and the normal conductorsare" omittedi The connector switch F is of the general type shown inUnited States'Letters Patent No. 815,17 6", issued March 13, 1906, toKeith, Erickson & Erickson.

A clearer understanding of my'imp'roved system may be had from an"explanation of its operation when employed in' releasing a connection.Assume, for example, that the subscriber at station A desires'toestablish connection with the substation A, the number of Which latteris 220: To call the number 220 the calling subscriber operates the dialin the usual manner for each digit of the desired number. When the dialis turned forward for the first digit 2 a pre-' liminary impulseenergizesthe trip magnet of the line switch C; This preliminary rotaryimpulse tooth 30 momentarily presses the rotary impulse spring 2% ontothe ground post 20, thereby closing an energizing circuit extending fromthe substation ground G through the cotiperating ground springs 18 and19, ground post 20, rotary impulse spring 24: to the rotary lineconductor 31, bridge-cutoff springs 56 and 57, trip magnet 55', throughthe motor magnet relay springs 58 and 59, interrupter springs 60 and 61through the winding of the motor magnet 62 to the battery lead 63. Themot6rn1agnet 62is not energized over this circuit, due to thecomparatively high resistanee of the'trip magnet 55; As soon as thetripjmagnet is energized its armature is attracted and theplunger thrustinto an idle bank terminal. When the plunger enters the bank terminal anenergizing circuit is closed througlithe motor magnet relay 6% of themaster switch. The motor magnet 62 in turn energizes and'operates torotate the ratchet wheel 65, thereby placing the idle pliinge'rsopposite the next idle bank terminal: The circuit through the relay 64extends from ground G through the winding 66 to theeommon segment 67 ofthe master switch bank,-through the wiper 68 to the individual segment69 (which corresponds to the trunk terminal just engaged), conductor 70,iiiieswitch bank springs 71 and 72, through the winding of the releasemagnet 73 tb the'battery lead 63, thence through battery B to ground G.Although this circuit includes the releasema-gnet 7 3, the said magnetdoes not operatively energize, since the relay 6% iswound to a highresistance, While the winding of the release magnet 73 is of acomparatively low resistance. The relay 64: u enenergi'zihg' operates toplace the spring 59 in contact with the spring 74, whereby the circuitis closed through the motor magnet 62, said circuit extending fromground through the relay springs 74 and 59, interrupter springs 60 and61, through the Winding of the motor magnet 62 to thebattery lead 63,thence through battery B- to ground G. The motor magnet upon energizingattracts its armature 75, whereby the pawlu'pon the end of the armature75 engages the ratchet Wheel and rotates' the' la'tter 'o'ne'step. Whenthe armature is attracted against the magnet cores theinterru tersprings 60 and 61 disengage, thereby breaking the energizing circuit ofthe motor magnet 62. vThe cam arm 76, beingin engagement with the pin 77 ,is operated to advance the plunger shaft 78, and consequently allidle plungers that may be in normal position, one step to another bankterminal. Also, the master switch bank wiper 68- is' carried from thecontact 69, which corresponds to the trunk line engaged, to anothercontact corresponding to the bank terminal before Which the idle lungersare now resting. At the instant that the plunger enters the bankterminal the bank springs are pressed into contact as fol lows: 71 and72, (9 and 80, 81 and 82, and 83 and 84. The engagement of the springs83 and 84 establishes a positive guarding.

potential which is transmitted by the private normal conductor 85 to theconnector private bank contact corresponding to the line of substationA. This potential protects the line of the calling subscriber from beingcalled by another while the protected line is in use. Also, when thesprings 83 and s4 engage, an energizing circuit is esof the springs 56,57 and 87 disconnects the subscribers line conductors 31 and 32 from theline switch trip magnet The guarding potential at the master switch bankfor protecting the trunk line conductors 89 and 90 from being seized byanother line switch extends from the battery lead 63, through therelease magnet 7 3 and bank springs 72 and 71, conductor to theindividual contact 69. The closure of connection between the springs 79and80 extends the subscribers vertical line conductor 32 to the trunkline conductor 89. In a similar manner the engagement of the banksprings 81 and 82 extends the subscribers rotary line conductor 31 tothe trunk line conductor The trunk line conductors 89 and 90 terminatein the first selector switch E, and now, when the dial returns to normalposition for the first digit, the vertical line relay is energized anumber of times, depending upon the digit called. The digit called being2, the vertical impulse spring 23 is pressed onto the ground post 20twice, thereby closing an energized circuit each time through thevertical line relay 91 of the first selector E. This circuit extendsfrom the substation ground G through the ground post and impulse spring23 to the vertical line conductor 32, bank springs 79 and 80, sideswitch wiper 92, vertical line relay 91 to the battery lead 63, thencethrough battery B to ground G. Each time that the vertical line relay 91energizes, the springs 93 and 94: are pressed into contact, therebyclosing a circuit through the vertical magnet 95 extending from ground Gthrough the springs 93 and 9 1, private magnet springs 96 and 97,vertical magnet 95 to the battery lead 63, thence through battery B toground G. The vertical magnet is thereby energized twice, and

the shaft and shaft wipers 98, 99 and 100 are raised one step at a timeuntil the shaft wipers are carried up two steps'and thus broughtopposite the bank level in which are located the terminals of trunklines leading to connector switches. Immediately. following the lastvertical impulse the rotary impulse spring 24 is pressed onto the groundpost 20, thereby energizing the rotary line relay 101 of the firstselector E; The circuit of the relay 101 extends from the ground post 20through the spring 24, rotary line 31, trunk conductor 90, side switchwiper 104 and relay 101 to the battery lead 63. The rotary line relayenergizes and places the springs 102 and 93 in contact, whereby anenergizing circuit is closed through the private magnet 103. The privatemagnet, as is Well known, controls the side switch Wipers 92, 104:, 105and 106. The private magnet 103, upon energizing and deenergizing,permits the side switch wipers to engage their respective contacts ofthe second position.' "When the side'switch wiper 105 engages thecontact point 107, an energizing circuit is closed through the rotarymagnet 108, said circuit extending from ground Gr through the sideswitch wiper 105, interrupter springs and windings of the rotary magnet108 to the'battery lead 63, thence through battery 13 to ground G. Therotary.

magnet upon energizing operates to rotate the shaft wipers 98, 99 and100 into engagement .withthe first bank contact of the second level. Ifthe first contact is busy a positive. guarding potential is present atthe private bank contact, and as soon as this contact isengaged by theshaft private wiper 100 an energizing circuit is established through theprivate magnet 103, said magnet in an energized position, therebylocking the sideswitch 1n second position until the private wiper 100passes onto a contact upon'which there is no guarding potential. At thatmoment the energizing circuit through the private magnet is broken andthe said magnet deenergizes, permitting the side switch to pass to thirdposition, whereby the energizing circuit through the rotary magnet isbroken.

Furthermore, when the side switch passes to third position a guardingpotential is established at thev private bank contact corre- 7 L Vspending to the trunk line engaged; This potential extends'from' groundG through the side switch wiper 106, back-release relay 109 to the shaftwiper 100, which engages" the private bank'contact. The subscribers lineconductors 31 and 32 are then extended to the conductors 110 and 111o'fthe con nector, when the sideswitch wipers 92 and 7 switch can notleave second position until two steps in a vertical direction, bringsare aiter theshaft has been rotated at least'one step. when the verticalline relay149 energizes, the relay springs 151 and 152 are pressed intocontact, thereby closiii'glthe circuit through the vertical magnet 153,said circuit extending from ground Gr through the springs 151 and 152,private magnet springs 154 and 5, side wiper 156, vertical magnet 153 toth'e battery lead 63, thence through battery B t6 ground G. The erticalmagnet operates and, by

shaft wipers 157,158 and 159 opposite the bank level in which arelocated the terminals of the line'1':220, Following the verticalimpulses the rotary liile relay energizes to place the springs 160 and151 nto contact to close a circu t through the prlvate magnet 161 whichoperates to place the] side switchwipers in second position. lVhen theside switch wiper 156 engagesits second-pesition contact point therotary magnet 162 is placed under the control of the vertical 11116relay, so that when the dial is operated fer the last digit 0, and thevertical relay 149 presses the springs 151 and 152 into contact tentimes, anfenergizing circuit is closed ten times through the rotarymagnet 162 in-' stead of through the vertical magnet 153. In response tothe operation of the dial for the last digit tl'ierotary magnet operatesto carry the shaft wipers 157 ,158 and 159 into engagement with thetenth contact of the second level of the connector bank, Follow ing thevertical impulses for the digit 0 the usual rotary impulse energizes therotary line relay 150, and again the private magnet 161 is energized topermit the side switch wipers 156, 163, 164 and 165 to pass to thirdposition. The engagement of the third-position contact point by thesideswitch wiper 156 places the verticalline relay 149 in control of theringer relay 166, in the same manner in which the rotary magnet 162 cameunder the control of the vertical line relay when the wiper 156 passedfrom first to second position. When the side switch wiper 165 passes tothird position a positive guarding potential is established at theprivate bank contact of the called line. Also, this guarding potentialprovides an energizing circuit for the bridge-cut-oti relay 167 of theline switch C of the called line. This energizing circuit extends fromground G through the side switch wiper 165 to the shaft wiper 159,thence over the normal conductor 168, through the winding of thebridge-cutoff relay 167 to the battery lead 63, thence through battery Bto ground G. This relay upon energizing operates to separate the springs169, 170 and 171 and to carry the springs 169 and 172. into contact. Theside switch wipers 163 and 164, upon passing to third position, extendthecalling subscribers line conductors 32 and to the normal conductors173 and 174' of the called line. The calling subscriber at substation Atherefore presses the signaling button 37, whereby an energizing circuitis established through the vertical linerelay 149 of the connector. Theconnector line relay operates to close a circuit through the ringerrelay 166, said circuit extending from ground G through the springs 151and 152, private magnet springs. 154 and 155, side switch wiper 156,through the winding of the ringer relay 166 to the battery lead 63,thence through battery 13 to ground G. I

The ringer relay uponenergizing operates to separate the calling andcalled lines, and to bridge across the latter the terminals of. theringer generator H, thereby transmitting signaling current to the'ringer44 01 the called substation #220. Thepath of the ringing current extendsfrom the generator H through the ringer springs 175 and 176, side switchwiper 163, shaft wiper 157 to the normal conductor 173, bridge-cut-ofisprings 1721antl 169 to the line conductor 177, switch hook 42 andspring 43, through the ringer condenser to the rotary line conductor178, normal conductor 174, shaft wiper 158, side switch wiper 164,ringer relay springs 179 and 180 back to the generator H. In response tothe signal the subscriber at substation removes the receiver from theswitch hook. When the receiver is removed the springs 46 and 47 engage,thereby closing the local battery circuit and providing the transmitter48 with talking battery current. The springs 49 and also engage andclose the line circuit through the receiver. The two substations beingprovided witlrtalking battery current, communication may be carried onover the conductors shown by heavy lines in Figs. 1 and 2.

The release of the central office switching apparatus occurs when thecalling subscriber restores the receiver 2 to the switch hook 3, andthereby grounds the vertical and rotary line conductors 32 and 31simultaneously, when the release springs 7, 8Tan'di9 come into contact.The vertical and rotary line relays 1 19 and 150 of the connector Fthere upon energize, and placethe release springs .181 and 182 incontact, which closes an energizing circuit through the release magnet183 in series with the back-release relay 109 of the first selectorswitch E. This circuit extends from ground G through the side switchwiper 106, back-release relay 109, shaft wiper 100, conductor 100,trunkrelease springs 181 and 182, release magnet 183 to the battery lead63, thence 1 through battery B to ground G. The release magnet 183thereupon energizes and operates to restore the shait wipers to normaland the side switch wipers to first position. The back-release relay 109also energizes and places the springs l84aand 185 in contact, whichcloses an energizing circuit for the release magnet 186 of the selectorE, saidcircuit extending fromground G through the springs 18% and 185and release magnet 186 to the battery lead 63, thence through battery Bto ground G. The re lease magnet 186 uponenergizing closes the armature187 in contact with the contact point 188, thereby providing anenergizing circuit forthe release relay 189. This circuit extends fromground G through the contact point 188, armature 187, release relay 189,springs 190 and 191, heat coil springs 192 and 193, bank springs 71 and7 2, release magnet 7 3 to the battery lead 63,

thence through battery 13 to ground G. The

the springs 190 and 196 into engagement with the springs 19a and 195,respectively. The engagement of the springs 190 and 194 provides a newenergizing circuitfor the relay 189 extending from ground G to thespring 190, as before, then through the spring 194;, resistance coil 197to the battery lead 63, thence through battery B to ground G. Theengagement of the springs 196 and 195 provides'a circuit for the releasemagnet '73 extending from ground G through the springs 195 and 196, heatcoil springs 192 and 193, bank springs 71 and 72, release magnet 73 tothe battery lead 63, thence through battery B to ground G. i The releasemagnet 73 thereupon energizes and attracts its armature, remaining inreadiness to withdraw the line switch plunger the release springs 7,8and 9 disengage, the line relays 1 19 and 150 of the connectordeenergize and break'the release circuit when All of I respectiveswitches to normal position in readiness for another operation.

The relay 189 deenergizes slowly after its energizing circuit is broken,so as to insure a sufliciently long impulse for releasing the switch C.This slow action may be obtained by placing a heavy copper ring aroundone end of the core of the relay. In order to make the operation of therelay 189 more positive, its springs should be adjusted to operate inthe following manner during its energization: First, the springs 190 and194 should come in contact, then the spring 190 should break contactwith the spring 191, and finally the spring 196 should engage the spring195. e

It will be seen that the subscriber at sub station A may operate thecentral office switches to establish connection with another subscriberat substation A, and after the termination 01 the conversation my improved release arrangement is employed to produce an effective releaseof the line switch from the first selector.

It will be seen that my invention is applicable to asystem of thatparticular type in which the subscribers are divided into groups, and inwhich 'the'connec'tors have vertical motion to select groups, and thenrotary motion to find the called subscriber in any selected group. 'Theten subscribers of each groupthat is to say, the ten dinerent levels ofeach connector-go to make up the larger group of one hundred sub-'scribers. Tie trunks are also, of course, divlded into groups, and theselectors have vertical motion to select groups, and then rotary motionto automatically find an idle The special trunk in any selected group.release. relays .189 areenergized. over the third conductors of thetrunks leadingfrorn the line switches C to the first selectors E, in anexchange of the character shown. It will be readily understood, however,that the switches C may be made individual to trunk lines as well as tosubscribers lines, and that the trunks leading from the switches Cfmayterminate in connectors or other switches as well as in selectors.Obviouslythese variations in the use of the relays 189 may be made ifdesired without departing fromthe spirit of my invention.

The off normal contacts X are connected with the armature 187, and areopened when the selector E is actuated from normal position. Thesupervisory relay Y is connected with said contacts, and with ground,and is energized when the selector is seized.

'lhesaid relay is energized oyer a circuit including thef windings ofthe relay 189 and i magnet 73, but at such time the" relay 189 'gize andmagnet 73 do not energize, as the refsistanCe 0f the relay Y is high.The supervisory lamp Z is operated and a signal displayed as soon as thetrunk is seized by the line switch. This lamp, it Will be seen, iscontrolled by the relay Y. In this ay the release trunk between the lineswitch and theselector is used also for supervisory purposes. It is forthis reason that the initial energizing current of the relay 189 isthrough the contacts 71 and 72, in the manner explained instead of tobattery direct. It Wlll also be seen that normally 'a circuit is closedfrom ground through the relays Y and 18 9, master svvitch Wiper 68 andupper Winding of the relay (ii to the battery, but the combinedresistance of'these relays is so high that none of them are energizedWhen thus connected in series. a

What I claim as my inventign is 1. A telephone exchange trunking systemline switch provided with a release magnet, a circuit forenergizing saidmagnet, a relay for controlling said circuit, atrunlr release circuitfor initially energizing said relay in series with the said magnet, andanother circuit closed by the relayfor energizing it in multiple withsaidniagnet.

A telephone exchange trunking system line switchprovided with releasemagnet, a release relay adapted to be energized over a circuit includingsaid magnet, and a supervisor-y relay adapted .to be energized in serieswith saidmagnet and relay, said supervisory relaybeing ofsutficientlyhigh resistance to prevent the said magnet and other relayfrom energizing. 3. A telephone exchange trunking system line sivitchprovided Witha release magnet, a release relay controlling the saidmagnet, and a supervisory relay adapted to be ener- 4 over acircuitincluding the ivinding of said release relay, said supervisoryrelay being ofsutliciently high resistance to prevent energizing ofthe'said release relay.

4. In a teleph one exchange trunking systern, a line switch providedwith a release relay and a releasemagnet controlled by said releaserelay, said relay having normally open and normally closed springs, 'acircuit for the magnet controlled byvnorrrallyopen springs of saidrelay, a circuit for said magnet .in-

cluding normally closed springsof said reseem-8.

a release magnet controlled by said release i relay, saidrelay havingthe springsl90, 191, 19%," 195 and 196, the springs 190 and 19-l adaptedto close before the springs 190 and 191open, and'the springs 195 and 196adapted to close together after the springs 190 and 191 separate, andcircuits for said magnet and relay controlled by said relay,substantially as andi'or the purpose set forth.

6.1111 a telephone system, a non-numerical line switch, trunks adaptedto be seized by said line switch, each trunk comprising talkingconductors and an auxiliary conductor disconnected therefrom, means forautomaticallyselecting idle trunks, a release magnet for said lineswitch, and a sloWacting relay in said auxiliary circuit for each trunkcontrolling said magnet, together ith a local grounded circuit forenergizing said magnet, controlled by said relay.

{7. a telephone system, a plurality of trunks, a release relay for oneend of each trunln'means to bereleased by said relay,

adapted to seize the same end of the trunk,

a third conductor for each trunk, and means atthe other end of eachtrunk for closing a release circuit over said third conductor in seriesWith the Winding of said release relay. 8. In a telephone 5 system,automatic switches, a trunk-release circuit, a supervisoryrelay, acircuit for said relay including a" portion of said trunk-releasecircuit, a signal controlled by said relay, and a switch adapted by itsinitial actuation from normal to open the circuit of said relay andthereby retire the said signal.

9. telephone exchange trunking system line switch provided with arelease magnet, a supervisory relay, a circuit for energizingsaid'relay, said circuit including the Winding of said magnet, theresistance of said relay being sufficient to prevent energizing of themagnet, a signal controlled by said relay, and means for automaticallyopening said circuit to retire thesignal.

Signed me at Portland, Multnomah county, Oregon, this 14th day of June,1909.

JOHAN L. -E. MEYER.

XVitnesses:

' OMER KIRBY,

L. M. ANTOINE.

Copies of this patent maybe obtained for five cents each, by addressingthe Commissioner of Patents.

WashingtonQ J). 0. i

